[pulseaudio-discuss] Revisiting 5.1/7.1 channel positions

[Arun Raghavan]

Hey folks,
I've written up a quick analysis of the channel positions we currently support, and what I think makes sense:

  https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/merge_requests/55#note_85318

The summary is that "Rear Left/Right" is currently being used in place of what should be "Left/Right Surround", and we do not have any channel  position between that position and "Rear Center", which is needed for common 7.1 configurations (what would be "Rear Left/Right Surround").

To add to this, the PulseAudio channelmap header is incorrect in that we say that "Side Left/Right" should correspond to Dolby "Surround Left/Right" when they are separate (they are further forward than "Surround Left/Right". Yhis can be corrected easily enough as it's just a documentation comment.

My proposal is to add a "Rear Left/Right of Center" position to represent the missing positions. At the ALSA level, it would correspond to RLC/RRC.

Any comments?

Regards,
Arun